Partial Rendering

Is there a way to render just a part of the model?
I tried “render selection” but it doesn’t render specific objects the same way as when the entire model is rendered.
In Accurender you could render a window selection when you didn't want to render the entire model. This is very useful if you want to change only one area in the image (with the help of Photoshop) without having to do a full rendering.

Thanks.

AG

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Permalink Reply by Boothy on September 10, 2011 at 11:47am

I do not know of any a present - a way around this is to `envelope` the selected area with six sections (effectively making a cube with section planes around the chosen area). As Irender see more than one section (makes sure you adjust to view all sections in settings tab) the remaining elements within cube should render in the same way has original full render. I have used this method lots of times to create a `patch` to overlay in PS later.

3D max also used to provide a `render window`- the render farmer seems to split up into horizontal segments so it might technically be possible. I think the developers have a long wish list.

Bit of a long workaround but worth it if the patch is for a long render. A ruby which creates the sections automatically from a drawn cube may be the way ?

Boothy

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Permalink Reply by Rich Hart on September 10, 2011 at 1:11pm

But it would be fairly easy to add a checkbox where we would automatically add those 6 section planes around the selected geometry for you, not as section planes in SketchUp , but just send them along to the rendering engine.

Would that do it?

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Permalink Reply by Boothy on September 10, 2011 at 1:16pm

Hi Rich

Sounds good

I have mentioned this in past but probably got lost with all the other wish list demands. Have would you define the `section geometry`?

Thanks

Boothy

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Permalink Reply by Render Plus on September 10, 2011 at 2:57pm

In response to the original question: When we render the selection, we actually render the selection and any "connected faces" as defined by SketchUp. We could try to get a render selection that truly renders only the selected geometry. (Of course, that would not include any unselected lights, or reflection from other surfaces.)

For now, you could select everything and hide it, then click "View hidden geometry", select the item you want to render, and unhide it. I just tried that and it worked. (It is ok to leave "View hidden geometry" on, we still only render the items which are not hidden.

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Permalink Reply by Boothy on September 11, 2011 at 3:41am

Hi Al

The `hidden` method proposed above - will this render associated effects of adjacent objects ? light bounce, reflections, shadow etc. The point of the question was to partial render a `patch` which will match original render.

Boothy

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Permalink Reply by Render Plus on September 11, 2011 at 8:08am

Arrgh! I need to learn to read more carefully.

AAdig wants to render just a windowed area of the model.We need to add this as a "Render Area" function on the rendered image. Until we write a re-render area function, you will have to use a complex sequence like this:

You can zoom-in and re-render a small area using the Change View, Orbit feature on the rendering Window toolbar, (You could zoom in, and change the size of the rendering to quickly re-render just a part of the image.

(This is probably too much work for what AAdig wanted to do - but it may help introduce you to the chnage view function in the rendering window. Another thing AAdig could do is to set a small rendering size in SketchUp, save the current view in SketchUp as an animation frame, and the zoom in as desired in SketchUp to save time by rendering a smaller area.)

In this sequence we are using the View Rotate function to zoom in on an area of the rendered view and re-render it at a smaller resolution.

1. After Rendering, Select the View/Rotate icon to load the View/Rotate window.

2. Change the view as desired - here we are using the Zoom-Window function to zoom in on an area of the original rendering.

3. We could select Render to re-render with the new view, but we want to change the screen size, so we will select Close to return to the rendering window.

4. Here we are setting a custom rendering size of 400 x 400

5. This is the new smaller rendering of the clipped area.

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Permalink Reply by Boothy on September 11, 2011 at 11:58am

Hi Al

I would think the `area render function`would primarily br required if you wanted to patch a small section of a long render without having to rerender the whole view again - in the above method you would have to rerender all of the image to get the `zoom sample `in the first place - or am I missing something ?

Boothy

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Permalink Reply by Render Plus on September 11, 2011 at 5:28pm

The area function will be great, and not that hard to do, but won't help much for geometry chagnes - just material changes.

The procedure I described will also work for material changes in small areas, but you will have to save and retore the original view when you are done.

A render area from Sketchup would be good for testing geometry changes without having to extract and render the whole model.

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Permalink Reply by Richcat on September 12, 2011 at 1:52am

I think accurender has some patch functinlity - but I may be wrong.

There is a "apply patch" in drop down "Image" menu in the nXtimage editor.

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Permalink Reply by Richcat on September 14, 2011 at 4:46pm

Its also recntly been mentioned in this discusion here by Roy.

"To reliably patch a region render into a larger render, you must save both in .nXtImage format and use the Image Editor Patch option. Both should have the same number of passes. Any other method will have exposure issues"